Downhole pumps are used to pump material such as oil and gas from beneath the surface of the earth. These pumps may be connected with downhole tubing that can extend far beneath the surface in order to extract the oil or gas. The pumps may be electrically controllable submersible pumps that are controlled and powered by an electric power supply disposed above the surface.
The power supply can control operation of the pumps by changing when the current is supplied to the pumps. Because the pumps may need to be operated according to a work cycle that includes some down time for the pumps, the power supply may periodically shut off power to one of the pumps while continuing to operate another pump.
Currently, the power supply is connected to the different pumps using separate cables. For each pump, a different cable extends from the power supply to the pump. In some instances, different cables extend from the power supply to each of the pumps, with different cables conducting different phases of a three-phase current to each of the pumps. In order to control (e.g., start or stop) conduction of current or a phase of current to a pump, the power supply starts or stops conducting the current along the respective cable.
Using many separate cables to power and control the pumps can add significant cost to pumping operations. In some instances, the cost of extending cables into the downhole tubing can be in excess of 40% of the total capital cost of the pumping operation. While some proposals for using mechanical switches and fewer cables to control the conduction of current have been made, these proposals are unlikely to operate in the extreme conditions associated with the pumping operations, where temperatures can exceed 200 degrees Celsius and/or pressures in excess of 20,000 pounds per square inch (e.g., 138,000 kilopascals). These conditions can limit the available mechanical switching solutions for controlling when different phases of current are supplied to the pumps to control the pumps.